This read-write INTEGER controls Residual Echo Control on this line, determining whether leftover echo after cancellation is left alone (cancelOnly), replaced with silence (suppressResidual), or masked with comfort noise at the ambient level (comfortNoise); reserved is not a usable value. This lets an admin fine-tune perceived call quality by deciding how any imperfect residual echo is handled after the primary cancellation stage. For example, if callers on a line report a faint lingering echo even with cancellation enabled, an admin might switch vismEcanREC to suppressResidual or comfortNoise to mask it.